This invention relates to an electronic lock assembly which is operated by inserting of an authorized electronic key. Rotation of the lock cylinder is inhibited until operation of the lock assembly is desired. Once the key is rotated, the key cannot be removed from the lock cylinder until the lock cylinder is rotated back to its original position, thereby giving the electronic lock the feel of a mechanical lock.
In many environments, such as apartment houses, multi-family dwellings, condominiums or the like, the transient nature of residents present problems in using conventional locking mechanisms in association with a door having a latch which is operable from both sides of the door by means of a handle or the like. In such environments, keys usable to unlock conventional lockable latching mechanisms are easily replicated, thereby potentially compromising the security provided by the lockable latching mechanism. As tenants or occupants move from such an environment, a key or copy of the key can be retained, though the former tenant or occupant is no longer entitled to access thereto. Similarly, if maintenance or repair procedures require access by other personnel, maintaining security may again be compromised if keys are duplicated or not returned by the repair or maintenance personnel. Thus, security standards in such environments may require that the lock be removed in its entirety and replaced, or the lockable latching mechanism is swapped with another mechanism from another unit to ensure security. Another alternative is to have the lockable latching mechanism re-keyed such that the previous key will not operate the mechanism. In each of these situations, the replacement, re-keying or swapping of the lockable latching mechanism is costly, both in terms of expense and/or personnel resources, and/or presents a time consuming and inefficient process for ensuring security.
Attempts have therefore been made to provide enhanced security by providing an electronic lock which employs a programmable processor which can be programmed to only allow operation of the lock if a valid key is used. Thus, upon a tenant or occupant leaving a premises, the electronic lock can simply be reprogrammed so that the old key will not operate the lock, thereby eliminating the need to replace or re-key the lock. Although electronic locks using card readers, key pads or contact activated data ports are known, various deficiencies in such electronic lock assemblies have been found, and such systems have generally been cost prohibitive or complex, thereby limiting widespread use in such environments.
Based upon the foregoing, the present invention is directed at an electronic lock assembly which is operable by a suitably programmed electronic key. The electronic lock assembly includes a cylinder type locking mechanism, where a solenoid and plunger is provided to electronically lock and unlock a key cylinder, thereby selectively allowing rotation of the key cylinder for operation of the locking mechanism. To prevent rotation of the key cylinder and loading of the solenoid plunger prior to the solenoid receiving an authorized signal to retract the plunger, a stop mechanism is provided which only allows rotation of the key cylinder in predetermined coordination with operation of the solenoid.
These and other aspects of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.